£50m is absolutely fine if you ask me. Yes, it's a hefty fee, but you have to take into consideration that we're bidding for the main man of an already wealthy club, it'll take a big offer to convince them to part with him. De Bruyne was nothing short of phenomenal last season, and I doubt he'll be a one-season wonder as he has a great hardworking attitude, in interviews it always seems like he's hungry to prove to people what he can do, particularly in the CL, so if anything he'll probably only get better.
We're going to have to pay out of our pockets for our three main targets this season, the goal is to take the extra step towards the CL now, combine this with prices always going up in modern football and these fees aren't as unreasonable as they might seem at first.